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within the cavity containing the embryo-sac certain of the spiral 

 filaments which I have already described; these are from two to 

 five or even more in number, and are perfectly free and never enclosed 

 in their respective cellules : for at this period the said filaments travel, 

 by the aid of their cilia, from the burst antheridium to the orifice 

 of the pistillidium, and entering its apical orifice, pass down the canal 

 to the embryo-sac. In this migration they are assisted by the muci- 

 lage in which they are enveloped, and by the moisture always present 

 on the under surface of the pro-embryo. It requires a practical 

 acquaintance with the figure and position of these filaments to detect 

 them after having entered the cavity : the wide apical opening of the 

 pistillidium, which as yet scarcely projects above the surface of the 

 pro-embryo, tends greatly to facilitate their entrance. 



" It sometimes happens at this period of the impregnation that we 

 notice a great quantity of dead spiral filaments around the cavity of 

 the nucleus ; they appear wound like an S, or like a circle or a spiral 

 figure. However, I have but seldom observed this appearance. As 

 the embryo- sac grows, and thus displaces the spiral filaments, the 

 canal of the papilla of the nucleus is formed in the manner above de- 

 scribed, and receives into it one or two, but seldom more of them ; 

 the rest fall to the bottom of the cavity of the embryo-sac. Before 

 their entrance into it they exhibit with advancing growth a distinct 

 swelling, which occurs especially in those subsequently received into 

 the canal. In the meantime the embryo-sac filled with blastema has 

 formed in its interior a parenchyma composed of several cells (endo- 

 sperm), appears green, aud has so increased in size that it almost fills 

 the cavity of the embryo-sac. One of the spiral filaments penetrates 

 by one of its extremities into the part of the embryo-sac turned to- 

 wards the canal. The penetrating end is that at which the smaller 

 enlargement is situated, which at the same time exhibits a green tint ; 

 the larger, club-shaped, granular end projects out into the canal of 

 the papilla of the nucleus : this usually encloses a little pear-shaped 

 cellule. Here an obstacle of no slight importance interferes with the 

 observation : the delicate filiform connexion of the two ends of the 

 spiral filament is usually torn by the pressure of the glass covering the 

 preparation, and thus we see only the separated ends, on in the ca- 

 nal, the other in the cavity for the embryo-sac. As soon as the first 

 swelling has reached the middle of the embryo-sac, it separates itself 

 from the spiral filament, and now forms in the embryo-sac a closed 

 globule, the germinal vesicle. The other end projecting into the 

 canal dies away. This appearance must not be confounded with the 



